Heart valve diseases are some of the most common cardiac diseases in China, and most of them are valve damage caused by rheumatic fever. In recent years, the aging population has led to an increasing incidence of valve degeneration (including calcification, mucoid degeneration, etc.) and valve damage caused by metabolic disorders in China.
Conventionally, heart valve surgery is an open-heart procedure conducted under general anesthesia, during which, following an incision made along the patient's sternum (sternotomy), the heart is stopped and blood flow is guided through a “heart-lung” bypass machine (extracorporeal circulation machine). Therefore, traditional heart valve replacement surgery is a highly traumatic operation with obvious accompanied risks and may bring to the patient transient disturbances caused by emboli and other issues associated with the use of the extracorporeal circulation machine, such that a complete recovery typically requires a couple of months. In addition, for the elders and some special population groups, the trauma of the surgery is unbearable and the recovery needs more time and is sometime even impossible.
Minimally invasive interventional surgery offers a variety of advantages, including needlessness of sternotomy, minimal trauma and quick recovery for the patients. In the recent ten years, interventional therapies have shown a tendency to be able to cope with not only all diseases curable by medical and surgical treatments but also some diseases that the surgical treatments could not handle. After entering the twenty-first century, researches on interventional therapies for heart valve diseases have been experiencing a notable acceleration. Percutaneous valve replacement technologies have evolved from experimental researches to small-scale clinical trials and the interventional therapies for heart valve diseases are likely to have breakthroughs in technical “bottlenecks” to achieve extensive clinical applications. This makes the technologies again a focus of research efforts in the field of interventional cardiology.
Currently, many manual delivery systems for a prosthetic valve have been developed. Examples of such delivery systems include those disclosed in Chinese Patent Application No. 201010150770.6 assigned to Hangzhou Venus Medical Instrument Co., Ltd., Chinese Patent Application No. CN200510110144.3 assigned to Wen Ning, Chinese Patent Application No. CN201080046790.7 assigned to Medtronic, Inc. (the U.S.) and Chinese Patent Application No. CN200780008324.8 assigned to Edwards Lifesciences Corp. (the U.S.). Mostly, these systems include an inner tube, an outer tube, a prosthetic valve and a push-pull mechanism. The inner tube includes a guide cone, a connector for the prosthetic valve, and the prosthetic valve is loaded on an intermediate section between the guide cone and the connector for the prosthetic valve of the inner tube and securely attached to the connector. The outer tube shields over the inner tube in order to cover the prosthetic valve and is movable along the outer surface of the inner tube. The push-pull mechanism is in operative connection with the guide cone of the inner tube as well as with the outer tube so as to deploy the prosthetic valve.
However, the manual delivery systems currently used for interventional procedures involves sophisticated operations, imposes demanding requirements on the operating physician and raises a considerable amount of risk in terms of faulty operations. Additionally, the required operations are laborious and prone to cause hand fatigue of the physician, which is one of the reasons that cause inaccuracy of the operation or misoperations and hence deterioration in surgical performance.
U.S. Patent Pub. No. US20110251683A1 discloses an improved delivery system which can be operated in two different modes, i.e., rotation and advancement/retraction, enabling different delivery speeds. This delivery system includes a mechanical actuator mechanism which in practical use can be manually rotated or advanced/retracted to perform corresponding control functionality. However, this mechanical delivery system has the following drawbacks:
1) It involves sophisticated operations, imposes demanding requirements on the operating physician and raises a considerable amount of risk in terms of faulty operations;
2) The required operations consist of manual rotation and push/pull motions, which are laborious and require the use of both hands. This tends to cause hand fatigue of the physician and thus affects accuracy of the operation and performance of the surgical procedure.
3) It suffers from imprecise catheter motions. Advancement or retraction of the outer tube in the delivery system is enabled by the physician manually pushing, pulling or rotating a proximal handle, which lacks accurate and reliable control of the outer tube's velocity and motion.